For increasing data transmission performance and reliability, the so-called multiple input and multiple-output technology (MIMO) may be used in wireless radio frequency telecommunications for transmitting information between a base station and a user equipment. The MIMO technology relates to the use of multiple send and receive antennas for a wireless communication at for example a base station or a user equipment. The MIMO technology forms the basis for coding methods which do not only use the temporal dimension but also the spatial dimension for transmitting information and, therefore, enables a space and time coding. Thus, the quality and data rate of the wireless communication may be increased.
When a large number of user equipments is arranged within a cell served by a base station having a plurality of antennas and transmitting information according to the above-described MIMO technology, such an arrangement is called a massive MIMO system. Typically, massive MIMO systems are expected in buildings such as offices, shopping malls and so on. In such an environment, a large number of user equipments can be expected. In massive MIMO systems, the configuration of the individual antenna transceivers of the base station may vary depending on the location of each of the user equipments and transmission conditions in the environment of the base station and the user equipment.
A massive MIMO system may be used in connection with a time division duplex (TDD) system in which a transmission of an information stream between the base station and a user equipment is split up into time slots or sections embedded in a frame structure. Different time slots for uplink (UL) data communications and downlink (DL) data communications may be provided for communicating information from the user equipment to the base station (uplink) and for communicating information from the base station to the user equipment (downlink). In such a massive MIMO system, there is a need for an additional time slot which may be called a “header” for transmitting a pilot signal or a training signal including a training sequence from the user equipment to the base station. Based on the received pilot signal, the base station may configure the transceivers of its antenna array according to spatial and environmental conditions for the subsequent transmission of payload information. This is usually done during the uplink slot during which the base station records the received signals and calculates the hermetian transpose of a footprint matrix determined from the training sequence. Thus, high antenna gain for the payload to be transmitted in the following time slots can be achieved. In general, payload may be transmitted in a number of uplink and downlink time slots.
A problem with such a frame structure is that the ratio between the uplink time slot and the downlink time slot can only be altered by decreasing the downlink time. This is due to the fact that the uplink time slot is needed for the calculation of the hermetian transpose of the footprint matrix.
However, especially in broadcasting scenarios, there may be an increased need for higher downlink capacities.
Therefore, it is the object of the invention to provide an improved method of operating a base station in a wireless radio network, especially in a wireless communication network using the MIMO technology, as well as a corresponding base station and a corresponding user equipment, which allow to increase the downlink capacity.